An appraisal of the phylogenetic relationships of Hypoptopomatini cascudinhos with description of two new genera and three new species (Siluriformes: Loricariidae)

Maria Laura S Delapieve,Roberto E Reis,Pablo Lehmann A

doi:10.1590/1982-0224-20170079

Abstract

ABSTRACT The discovery of three new taxa of Hypoptotopomatini with ambiguous generic assignment prompted a reanalysis of the phylogenetic relationships of the tribe. The analysis focused on a data matrix of 56 terminals and 107 morphological characters comprising the three new taxa, most species of Hypoptopoma and Otocinclus, and all other species of the tribe. The 162 maximally parsimonious trees of 382 steps, consistency index of 0.41, and retention index of 0.83 were then summarized in a strict consensus tree. The results confirm the monophyly of the Hypoptopomatini, recover four genera as monophyletic (Acestridium, Hypoptopoma, Niobichthys, and Otocinclus), revealed Hypoptopoma and Oxyropsis to be non-monophyletic; and revealed two new genera within Hypoptopomatini. Additionally, Otocinclus was found to be sister to a group with all remaining genera of the tribe; Acestridium and Niobichthys were found to be sister to each other and that clade sister to a group formed by ((Leptotocinclus + Hypoptopoma [part]) + (Nannoxyropsis (Oxyropsis + Hypoptopoma [part]))). Based on this framework, changes to the classification and the taxonomy of the Hypoptopomatini are suggested and the new taxa are described.

Highlights

Hypoptopomatini is placed in the subfamily Hypoptopomatinae, one of the six currently recognized subfamilies of the Loricariidae
Isbrücker’s study was not based on a phylogenetic analysis, the hypoptopomatines soon became the focus of several works involving cladistic analyses
Morphometric measurements were treated as percents of standard length (SL), except for subunits of the head that were treated as percents of head length (HL)

Summary

Introduction

Hypoptopomatini is placed in the subfamily Hypoptopomatinae, one of the six currently recognized subfamilies of the Loricariidae. The 46 known species of the Hypoptopomatini are largely distributed throughout the neotropics, occurring from the La Plata basin to the Orinoco basin and in coastal streams of southern and southeastern Brazil. In those basins they are found in small streams characterized by clear to turbid and well oxygenated water with moderate flow (Schaefer, 1997). When recognized by Isbrücker (1980), Hypoptopomatini included only the genus Hypoptopoma Günther, 1868 comprising the subfamily Hypoptopomatinae along with the tribe Otocinclini. Isbrücker’s study was not based on a phylogenetic analysis, the hypoptopomatines soon became the focus of several works involving cladistic analyses

Methods

Results

Conclusion